1. Field of the Invention
The present invention relates to a liquid crystal display device including a driver.
2. Description of the Related Art
A liquid crystal display device comprises a liquid crystal panel for displaying an image, a printed circuit board arranged along one side of the liquid crystal panel, and a plurality of flexible printed circuit boards connecting the liquid crystal panel and the printed wiring board and having driver ICs mounted thereon (for example, Japanese Unexamined Patent Publication (Kokai) No. 9-44100 and No. 7-49657). Source bus electrodes are arranged along one side of the liquid crystal panel and gate bus electrodes are arranged along another side of the liquid crystal panel. The source bus electrodes are mainly described here, that is, the description of one side of the liquid crystal panel is given here.
Each flexible printed circuit board has a drive IC. Display data signals, voltage signals and control signals are input to the input terminals of the printed circuit board. The output terminals of the printed circuit board are connected to the input terminals of the flexible printed circuit board and the input terminals of the flexible printed circuit board are connected to the driver IC. The driver IC converts the input signals into liquid crystal drive signals, which are then supplied to the source bus terminals of the liquid crystal panel via the output terminals of the flexible printed circuit board. The liquid crystal is driven by the input signals supplied in this manner.
Recently, as the liquid crystal display device has become more compact and its resolution has become finer, the number of input and output terminals of the flexible printed circuit board has increased, resulting in an arrangement of input and output terminals with a narrower pitch. The input terminals of the flexible printed circuit boards are connected to the output terminals of the printed circuit board with an anisotropic conductive adhesive (ACF). As the pitch of the input terminals of the flexible printed circuit board becomes narrower, the pitch of the output terminals of the printed circuit board to be connected thereto also becomes narrower.
If the pitch of the output terminals of the printed circuit board becomes, for example, 0.3 mm or less, the pitch of the input terminals of the flexible printed circuit board may become different from that of the output terminals of the printed circuit board, resulting in shift in position, owing to the thermal contraction of the printed circuit board material, when the flexible printed circuit board and the printed circuit board are bonded with the ACF. However, if a special material with low coefficient of contraction is used for the printed circuit board, the cost of the printed circuit board is increased.